Periodic Table of Elements
Click any element for detailed information — atomic mass, electron configuration and more
About the Periodic Table
The periodic table organises all known chemical elements by atomic number (number of protons), electron configuration, and recurring chemical properties. Elements are arranged in rows (periods) and columns (groups), with elements in the same group sharing similar properties.
Reading the Table
Each cell shows the element's atomic number (top), chemical symbol (centre), name and atomic mass (bottom). Elements in the same column (group) have the same number of valence electrons and similar chemical behaviour. Elements in the same row (period) have the same number of electron shells.
Why the Gaps?
The two rows at the bottom (lanthanides and actinides) are removed from the main table to keep it compact. They belong between elements 56/88 and 72/104 respectively. The gaps in periods 1–3 represent groups where no elements with that configuration exist for lighter atoms.
From the Blog
// Mendeleev's Table
Dmitri Mendeleev published the first periodic table in 1869, leaving gaps for undiscovered elements. Three were found within his lifetime — gallium, scandium and germanium.
// Most Abundant
Oxygen is the most abundant element in Earth's crust (46%). In the universe, hydrogen dominates at ~75% by mass.
// Noble Gases
Noble gases (group 18) have full outer electron shells, making them almost entirely unreactive. Helium never forms compounds under normal conditions.
// Newest Elements
Elements 113–118 (Nihonium to Oganesson) were confirmed between 2015–2016. All are synthetic and highly radioactive with very short half-lives.